While the IPA (India Pale Ale) has existed for centuries, the IPL is a modern invention of the craft beer movement. An IPL uses the same heavy hopping techniques as an IPA but uses lager yeast and cold fermentation temperatures. This results in a 'cleaner' profile because lager yeast produces fewer esters (fruity flavors) and phenols (spicy flavors) than ale yeast. This lack of yeast character allows the nuances of the hops to shine even more clearly. The science involves the difference between *Saccharomyces cerevisiae* (top-fermenting ale yeast) and *Saccharomyces pastorianus* (bottom-fermenting lager yeast). The IPL represents a bridge between the refreshing crispness of a traditional pilsner and the intense aroma of a modern IPA.